U.S. patent application number 16/474985 was filed with the patent office on 2019-10-24 for method for calibration of laser targeting projector and c-arm image, recording medium for performing the same and laser surgical.
The applicant listed for this patent is KYUNGPOOK NATIONAL UNIVERSITY INDUSTRY-ACADEMIC COOPERATIONFOUNDATION. Invention is credited to Sanghyun JOUNG, Hyunwoo LEE, Chulwoo PARK, Ilhyung PARK.
Application Number | 20190321125 16/474985 |
Document ID | / |
Family ID | 62635160 |
Filed Date | 2019-10-24 |
United States Patent
Application |
20190321125 |
Kind Code |
A1 |
PARK; Ilhyung ; et
al. |
October 24, 2019 |
Method for Calibration of Laser Targeting Projector and C-arm
Image, Recording Medium for Performing the Same and Laser Surgical
Guidance System Including Calibration Tool
Abstract
Provided is a laser surgical guidance system including a C-arm
fluoroscopy (hereinafter, C-arm) to identify a patient's condition
and support a surgical plan and a laser targeting projector to
project a line of the surgical plan directly onto an affected part
through a line projection module which generates a laser. The laser
surgical guidance system may generate a particular laser pattern
from the line projection module, transmit the particular laser
pattern outputted from the line projection module through a
calibration tool including a collimator having a particular
orientation, calculate an extrinsic parameter of the calibration
tool in a projection image having passed through the calibration
tool, and convert coordinates of the C-arm image into the line
projection module coordinates using the extrinsic parameter.
Inventors: |
PARK; Ilhyung; (Daegu,
KR) ; LEE; Hyunwoo; (Daegu, KR) ; JOUNG;
Sanghyun; (Daegu, KR) ; PARK; Chulwoo; (Daegu,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KYUNGPOOK NATIONAL UNIVERSITY INDUSTRY-ACADEMIC
COOPERATIONFOUNDATION |
Daegu |
|
KR |
|
|
Family ID: |
62635160 |
Appl. No.: |
16/474985 |
Filed: |
November 29, 2017 |
PCT Filed: |
November 29, 2017 |
PCT NO: |
PCT/KR2017/013769 |
371 Date: |
June 28, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2090/3966 20160201;
A61B 6/505 20130101; A61B 17/1703 20130101; A61B 2090/366 20160201;
A61B 90/361 20160201; A61B 90/37 20160201; A61B 2090/365 20160201;
A61B 6/4275 20130101; G06T 19/006 20130101; A61B 2090/3764
20160201; A61B 2017/00725 20130101; A61B 90/36 20160201; A61B
2090/376 20160201; A61B 90/13 20160201; A61B 2090/3937 20160201;
G06T 2207/30008 20130101 |
International
Class: |
A61B 90/00 20060101
A61B090/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 29, 2016 |
KR |
10-2016-0181943 |
Claims
1-17. (canceled)
18. A laser surgical guidance system comprising: a C-arm
fluoroscopy (C-arm) identifying a patient's condition and
supporting a surgical plan, and a laser targeting projector
projecting a line of the surgical plan directly onto an affected
part, the laser targeting projector comprising: a line projector
generating a laser; a calibration tool spaced apart a predetermined
distance from the line projector, and including a collimator having
a particular orientation for transmitting a particular laser
pattern outputted from the line projector; and a calibrator which
calculates an extrinsic parameter of the calibration tool in a
projection image having passed through the calibration tool, and
converts coordinates of the C-arm image into the line projector
coordinates.
19. The laser surgical guidance system according to claim 18,
wherein the calibration tool includes: a light pattern matching
unit including the collimator having the particular orientation for
transmitting the particular laser pattern outputted from the line
projector; and a C-arm marker unit including bearing balls arranged
in a matrix to calculate the extrinsic parameter of the calibration
tool, wherein the laser pattern having passed through the
collimator is recognizable in the projection image.
20. The laser surgical guidance system according to claim 19,
wherein the collimator of the light pattern matching unit is formed
in an opening pattern, and the opening pattern is formed at a
predetermined angle.
21. The laser surgical guidance system according to claim 19,
wherein the calibration tool further includes a screen disposed
between the light pattern matching unit and the C-arm marker unit
to check the laser pattern having passed through the
collimator.
22. The laser surgical guidance system according to claim 19,
wherein the bearing balls are arranged in a 6.times.9 matrix.
23. The laser surgical guidance system according to claim 18,
wherein the calibrator derives a conversion matrix between the
C-arm image coordinates and the line projector coordinates using a
preset intrinsic parameter of the C-arm and the extrinsic parameter
of the calibration tool.
24. The laser surgical guidance system according to claim 18,
wherein the calibrator matches the coordinates of origin of the
C-arm image coordinates and the line projector coordinates.
25. The laser surgical guidance system according to claim 18,
wherein the line projector further includes at least one of an
optical apparatus to project the line, a CMOS camera to simulate
the C-arm, and a sensor to measure a distance from an object.
26. The laser surgical guidance system according to claim 25,
wherein the optical apparatus includes at least one of a
Galvano-mirror, a MEMS mirror, and a Diffuser lens.
27. A calibration tool for performing a method for calibration of a
laser targeting projector and a C-arm image, the calibration tool
comprising: a light pattern matching unit spaced apart a
predetermined distance from the laser targeting projector, and
including a collimator having a particular orientation for
transmitting a particular laser pattern outputted from the laser
targeting projector; a screen for checking the laser pattern having
passed through the collimator; and a C-arm marker unit including
bearing balls arranged in a matrix to calculate an extrinsic
parameter, wherein the laser pattern having passed through the
screen is recognizable by a C-arm fluoroscopy (C-arm).
28. The calibration of claim 27, wherein the collimator of the
light pattern matching unit is formed in an opening pattern, and
the opening pattern is formed at a predetermined angle.
29. The calibration tool of claim 27, wherein the bearing balls are
arranged in a 6.times.9 matrix.
30. A method for calibration of a laser targeting projector and a
C-arm image in a laser surgical guidance system, wherein the laser
surgical guidance system comprises a C-arm fluoroscopy (C-arm)
identifying a patient's condition and supporting a surgical plan;
and the laser targeting projector projecting a line of the surgical
plan directly onto an affected part through a line projector which
generates a laser, the method comprising: generating a particular
laser pattern from the line projector; transmitting the particular
laser pattern outputted from the line projector through a
calibration tool including a collimator having a particular
orientation; calculating an extrinsic parameter of the calibration
tool in a projection image having passed through the calibration
tool; and converting coordinates of the C-arm image into the line
projector coordinates using the extrinsic parameter.
31. The method of claim 30, wherein the step of the converting
comprises deriving a conversion matrix between the C-arm image
coordinates and the line projector coordinates using a preset
intrinsic parameter of the C-arm and the extrinsic parameter of the
calibration tool.
32. The method of claim 30, wherein the step of the converting
comprises matching the coordinates of origin of the C-arm image
coordinates and the line projector coordinates.
33. The method of claim 30, further comprising: projecting the
projection image having undergone calibration of the coordinates of
the C-arm image and the line projector coordinates directly onto
the affected part.
34. A non-transitory computer-readable recording medium having
recorded thereon a computer program for performing the method for
calibration of a laser targeting projector and a C-arm image
according to claim 30.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a method for calibration
of a laser targeting projector and a C-arm image, a recording
medium for performing the same and a laser surgical guidance system
including a calibration tool, and more particularly, to a method
for calibration of a laser device for marking a surgical plan in a
C-arm image onto an affected part and a calibration tool
therefor.
BACKGROUND ART
[0002] In case that a surgical plan is made using an imaging
device, it is difficult to perform a surgery as planned in the real
surgical field. For example, in osteotomy, when an osteotomy is
planned to be done 5 cm inferior to the knee joint, surgery needs
to be performed with 5 cm incision made using the ruler at the real
knee exposed through skin incision. However, there may be a huge
difference between the real surgery and the planned one depending
on the location and angle of the ruler.
[0003] Particularly, in the case of the technique for marking the
site of perforation at surgery using a writing tool in reliance on
the manual operation of the medical staff, especially when
perforation is needed, because the medical staff has to rely on a
2D image of a C-arm fluoroscopy, it fails to provide critical
information about whether to insert a surgical instrument
vertically or obliquely into a target affected part inside the
patient's skin. Therefore, surgery is performed relying on the
surgical experience or intuition of the medical staff.
[0004] Moreover, surgery outcome in an operation room greatly
depends on the surgical experience of the medical staff involved in
the surgery or their medical ability to interpret the affected part
image information, and thus in the case of the medical staff having
so little surgical experience, a considerate length of continuous
preparation and training period is required for accurate surgery,
resulting in the increased labor and material costs required for
training.
[0005] Accordingly, guidance for accurately performing a surgery as
planned is required. The conventional art involves obtaining an
image of a patient using machine such as Computed Tomography (CT),
magnetic resonance (MR) equipment, installing a marker at a
predetermined part of the patient such as a leg in an operation
room (the marker is an auxiliary instrument for matching the
coordinates), and calibrating (calibrating coordinates) an image
captured through MRI in the operation room using the corresponding
marker.
[0006] Accordingly, two processes, namely, placing the marker on
the patient's body and matching between the marker and the image,
are required, and thus the surgical procedure is complex and it is
impossible to provide real-time guidance. Additionally, imprecise
matching between the marker and the image may adversely affect the
surgical operation requiring high-level accuracy.
[0007] Particularly, in orthopedic surgeries, surgery is often
performed after identifying the condition of a bone using a mobile
C-arm fluoroscopy (hereinafter, C-arm) and making a surgical plan
for cutting and reshaping of the bone. Currently, to this end, a
k-wire (a stainless-steel wire) is placed at an affected part, a
C-arm image is captured, and a surgical plan is made taking into
account the positions of the bone and the k-wire.
[0008] A laser targeting projector is used to mark the planned
lines in the C-arm image directly onto the affected part, and
accurate spatial calibration between the laser target device and
the C-arm necessary to use the laser targeting projector is
essential.
RELATED LITERATURES
Patent Literature 1 KR 10-1650620 B1
[0009] (Non-Patent Literature 1) Z. Zhang, "A flexible new
technique for camera calibration", IEEE Transactions on Pattern
Analysis and Machine Intelligence, 22(11):1330-1334, 2000
DISCLOSURE
Technical Problem
[0010] In this context, the technical problem of the present
disclosure addresses the above-described issue, and therefore the
present disclosure is directed to providing a laser surgical
guidance system including a calibration tool.
[0011] The present disclosure is further directed to providing a
calibration tool for performing a method for calibration of a laser
targeting projector and a C-arm image.
[0012] The present disclosure is further directed to providing a
method for calibration of a laser targeting projector and a C-arm
image.
[0013] The present disclosure is further directed to providing a
recording medium having recorded thereon a computer program for
performing a method for calibration of a laser targeting projector
and a C-arm image.
Technical Solution
[0014] To achieve the above-described object of the present
disclosure, a laser surgical guidance system according to an
embodiment includes a C-arm fluoroscopy (hereinafter, C-arm) to
identify a patient's condition and support a surgical plan and a
laser targeting projector to project a line of the surgical plan
directly onto an affected part, and the laser targeting projector
includes a line projection module which generates a laser, a
calibration tool that is spaced apart a predetermined distance from
the line projection module, and including a collimator having a
particular orientation for transmitting a particular laser pattern
outputted from the line projection module, and a calibration unit
which calculates an extrinsic parameter of the calibration tool in
a projection image having passed through the calibration tool, and
converts coordinates of the C-arm image into the line projection
module coordinates.
[0015] In an embodiment of the present disclosure, the calibration
tool may include an light pattern matching unit including the
collimator having the particular orientation for transmitting the
particular laser pattern outputted from the line projection module,
and a C-arm marker unit including bearing balls arranged in a
matrix to calculate the extrinsic parameter of the calibration tool
so that the laser pattern having passed through the collimator is
recognizable in the projection image.
[0016] In an embodiment of the present disclosure, the collimator
of the light pattern matching unit may be formed in an opening
pattern, and the opening pattern may be formed at a predetermined
angle.
[0017] In an embodiment of the present disclosure, the calibration
tool may further include a screen formed between the light pattern
matching unit and the C-arm marker unit to see the laser pattern
having passed through the collimator.
[0018] In an embodiment of the present disclosure, the bearing
balls may be arranged in a 6.times.9 matrix.
[0019] In an embodiment of the present disclosure, the calibration
unit may derive a conversion matrix between the C-arm image
coordinates and the line projection module coordinates using a
preset intrinsic parameter of the C-arm and the extrinsic parameter
of the calibration tool.
[0020] In an embodiment of the present disclosure, the calibration
unit may match the coordinates of origin of the C-arm image
coordinates and the line projection module coordinates.
[0021] In an embodiment of the present disclosure, the line
projection module may further include at least one of an optical
apparatus to project the line, a CMOS camera to simulate the C-arm
and a sensor to measure a distance from an object.
[0022] In an embodiment of the present disclosure, the optical
apparatus may include at least one of a Galvano-mirror, a MEMS
mirror and a Diffuser lens.
[0023] To achieve another object of the present disclosure as
described above, a calibration tool for performing a method for
calibration of a laser targeting projector and a C-arm image
according to an embodiment includes a light pattern matching unit
spaced apart a predetermined distance from the laser targeting
projector, and includes a collimator having a particular
orientation for transmitting a particular laser pattern outputted
from the laser targeting projector, a screen for seeing the laser
pattern having passed through the collimator, and a C-arm marker
unit including bearing balls arranged in a matrix to calculate an
extrinsic parameter so that the laser pattern having passed through
the screen is recognizable by a C-arm.
[0024] In an embodiment of the present disclosure, the collimator
of the light pattern matching unit may be formed in an opening
pattern, and the opening pattern may be formed at a predetermined
angle.
[0025] In an embodiment of the present disclosure, the bearing
balls may be arranged in a 6.times.9 matrix.
[0026] To achieve still another object of the present disclosure as
described above, a method for calibration of a laser targeting
projector and a C-arm image according to an embodiment in a laser
surgical guidance system includes a C-arm to identify a patient's
condition and support a surgical plan, and the laser targeting
projector to project a line of the surgical plan directly onto an
affected part through a line projection module which generates a
laser includes generating a particular laser pattern from the line
projection module, transmitting the particular laser pattern
outputted from the line projection module through a calibration
tool including a collimator having a particular orientation,
calculating an extrinsic parameter of the calibration tool in a
projection image having passed through the calibration tool, and
converting coordinates of the C-arm image into the line projection
module coordinates using the extrinsic parameter.
[0027] In an embodiment of the present disclosure, the method of
converting the coordinates of the C-arm image into the line
projection module coordinates using the extrinsic parameter may
include deriving a conversion matrix between the C-arm image
coordinates and the line projection module coordinates using a
preset intrinsic parameter of the C-arm and the extrinsic parameter
of the calibration tool.
[0028] In an embodiment of the present disclosure, the method of
converting the coordinates of the C-arm image into the line
projection module coordinates using the extrinsic parameter may
include matching the coordinates of origin of the C-arm image
coordinates and the line projection module coordinates.
[0029] In an embodiment of the present disclosure, the method for
calibration of a laser targeting projector and a C-arm image may
further include projecting the projection image having undergone
calibration of the coordinates of the C-arm image and the line
projection module coordinates directly onto the affected part.
[0030] To achieve yet another object of the present disclosure as
described above, a computer-readable recording medium according to
an embodiment has recorded thereon a computer program for
performing the method for calibration of a laser targeting
projector and a C-arm image.
Advantageous Effects
[0031] According to the method for calibration of a laser targeting
projector and a C-arm image, it is possible to achieve accurate
spatial calibration between the laser module and the C-arm using
the calibration tool, thereby providing accurate laser guidance.
Additionally, it is possible to indicate a variety of surgery
information including osteotomy lines, needle trajectories, and pin
insertion position and insertion angle, thereby achieving accurate
surgery as planned, and reducing the likelihood of surgical errors
and medical malpractice. Further, it is possible to achieve quick
and accurate surgery according to the imaging plan while reducing
the dose of radiation exposure to the surgeon.
DESCRIPTION OF DRAWINGS
[0032] FIG. 1 is a conceptual diagram of a laser surgical guidance
system according to an embodiment of the present disclosure.
[0033] FIG. 2 is an exemplary diagram showing a projection image
represented by a laser targeting projector of FIG. 1.
[0034] FIG. 3 is a diagram illustrating a spatial calibration
algorithm of the present disclosure.
[0035] FIG. 4 is a diagram showing a calibration tool according to
an embodiment of the present disclosure.
[0036] FIG. 5A to FIG. 5D are diagrams showing each part of the
calibration tool of FIG. 4 and assembly of the parts.
[0037] FIG. 6 is a diagram showing a calibration tool scanned by a
C-arm.
[0038] FIG. 7 is a diagram showing the laser projection test result
for indicator points in implementing the present disclosure.
[0039] FIG. 8A to FIG. 8B are graphs showing projection precision
vs targeting distance in implementing the present disclosure.
[0040] FIG. 9 is a flowchart of a method for calibration of a laser
targeting projector and a C-arm image according to an embodiment of
the present disclosure.
DETAILED DESCRIPTION OF MAIN ELEMENTS
[0041] 1: Laser surgical guidance system
[0042] 10: C-arm fluoroscopy
[0043] 30: Laser targeting projector
[0044] 32: Laser
[0045] 34, 36, 38: Osteotomy line
[0046] 50: Line projection module
[0047] 70: Calibration tool
[0048] 71: Light pattern matching unit
[0049] 73: Screen
[0050] 75: C-arm marker unit
Best Mode
[0051] The following detailed description of the present disclosure
is made with reference to the accompanying drawings, in which
particular embodiments for practicing the present disclosure are
shown for illustration purposes. These embodiments are described in
sufficient details for those skilled in the art to practice the
present disclosure. It should be understood that various
embodiments of the present disclosure are different but do not need
to be mutually exclusive. For example, particular shapes,
structures and features described herein in connection with one
embodiment can be embodied in other embodiment without departing
from the spirit and scope of the present disclosure. It should be
further understood that changes can be made to positions or
placement of individual elements in each disclosed embodiment
without departing from the spirit and scope of the present
disclosure. Accordingly, the following detailed description is not
intended to be taken in limiting senses, and the scope of the
present disclosure, if appropriately described, is only defined by
the appended claims along with the full scope of equivalents to
which such claims are entitled. In the drawings, similar reference
signs denote same or similar functions in many aspects.
[0052] Hereinafter, the preferred embodiments of the present
disclosure will be described in more detail with reference to the
accompanying drawings.
[0053] FIG. 1 is a conceptual diagram of a laser surgical guidance
system according to an embodiment of the present disclosure. FIG. 2
is an exemplary diagram showing a projection image represented by a
line projection module of FIG. 1.
[0054] In orthopedic surgeries, surgery is often performed after
identifying the condition of a bone using a mobile C-arm
fluoroscopy (hereinafter, C-arm) and making a surgical plan for
cutting and reshaping of the bone. Currently, to this end, a k-wire
(a stainless-steel wire) is placed in an affected part, a C-arm
image is captured, and a surgical plan is made taking into account
the positions of the bone and the k-wire.
[0055] A laser targeting projector is used to mark planned lines in
a C-arm image directly onto an affected part, and the present
disclosure proposes a method for spatial calibration between the
laser targeting projector and a C-arm necessary to use the laser
targeting projector, and a tool therefor.
[0056] The laser surgical guidance system 1 (hereinafter, system)
according to the present disclosure calibrates a laser targeting
projector and a C-arm image using a calibration tool to help to
perform a laser surgery precisely and easily.
[0057] Referring to FIG. 1, the system 1 according to the present
disclosure includes a C-arm 10 to identify a patient's condition
and support a surgical plan, and a laser targeting projector 30 to
generate a laser 32 and project a line of the surgical plan
directly onto an affected part. The system 1 may be mobile or
fixed.
[0058] The system 1 of the present disclosure may be where software
(application) for performing calibration of the laser targeting
projector 30 and the C-arm 10 image may be installed and executed,
and the configuration of the C-arm 10 and the laser targeting
projector 30 may be controlled by the software for performing
calibration of the laser targeting projector 30 and the C-arm 10
image, executed in the system 1.
[0059] The configuration of the C-arm 10 and the laser targeting
projector 30 may be formed as a terminal, or may be formed as
separate modules and connected via a wired/wireless network. In
another example, the system 1 may be part of a robot system or a
robot arm that performs surgical guidance.
[0060] The system 1 may be mobile or fixed. The system 1 may have a
form of a device, an apparatus, a terminal, equipment, a server or
an engine, and may be called by another name.
[0061] Referring to FIG. 2, the laser targeting projector 30 is a
device that projects particular osteotomy lines and feature points
in a C-arm image directly onto an affected part using a laser.
[0062] When a user (for example, a surgeon) marks an osteotomy line
34 according to the surgical plan onto an image of leg bone
displayed on a display unit, the image showing surgery information
is directly displayed on the affected part such that it matches the
human body. Additionally, the user may modify, for example, change
or delete, the osteotomy line directly marked on the image of
bone.
[0063] The osteotomy line refers to a line planned when cutting
bones for the treatment of fractures or jaw surgeries.
Additionally, the osteotomy line may be marked in a line shape as
well as various shapes such as a crossing point 36 and a circle
38.
[0064] The surgery information that may be directly inputted from
the user includes all information that may be reflected on the
surgical plan, including the osteotomy line as well as a fixing pin
insertion position and insertion pathway, and needle
trajectories.
[0065] The laser targeting projector 30 may further include an
optical apparatus to project the line, a CMOS camera to simulate
the C-arm and a sensor to measure the distance from an object.
[0066] The optical apparatus may include a Galvano-mirror, a MEMS
mirror and a diffuser lens. In an embodiment of the present
disclosure, a Galvano-mirror may be used for the optical
apparatus.
[0067] Referring to FIG. 3, the laser targeting projector 30
includes a line projection module 50 to generate a laser, a
calibration tool 70 and a calibration unit (not shown).
[0068] Referring to FIG. 4, the line projection module 50 generates
a laser pattern of a particular shape, and the calibration tool 70
is disposed to allow the laser pattern to pass through the
calibration tool 70. Additionally, a C-arm 10 image is captured,
and the location of a C-arm marker of the calibration tool 70 is
calculated, thereby achieving spatial calibration between the C-arm
10 image and the laser targeting projector 30.
[0069] The line projection module 50 generates a particular laser
pattern, and the calibration tool 70 is spaced apart a
predetermined distance from the line projection module, and
includes a collimator having a particular orientation for
transmitting the particular laser pattern outputted from the line
projection module.
[0070] The calibration unit calculates the extrinsic parameter of
the calibration tool in a projection image having passed through
the calibration tool 70, and converts the coordinates of the C-arm
image into the line projection module coordinates.
[0071] Referring to FIG. 5 (5A to 5D), the calibration tool 70
includes a light pattern matching unit 71 and a C-arm marker unit
75. The calibration tool 70 may further include a screen 73
disposed between the light pattern matching unit 71 and the C-arm
marker unit 75.
[0072] The light pattern matching unit 71 includes a collimator
having a particular orientation for transmitting the particular
laser pattern outputted from the line projection module 50.
[0073] The pattern of the collimator may be configured under the
assumption that the laser beam comes from one point (a pin hole)
after being reflected at the Galvanometer. That is, the collimator
may be formed in an enlarged pattern having the same shape as the
particular laser pattern outputted from the line projection module
50.
[0074] The collimator of the light pattern matching unit 71 is
formed in an opening pattern, and the opening pattern is formed at
a predetermined angle. That is, as shown in FIG. 4, light passes
through the collimator obliquely according to the properties of
light such as linearity, orientation and scattering.
[0075] The screen 73 is a flat screen for seeing the laser pattern
having passed through the collimator.
[0076] The C-arm marker unit 75 includes bearing balls arranged in
a matrix to calculate the extrinsic parameter of the calibration
tool 70 so that the laser pattern having passed through the
collimator can be recognized in the projection image. In an
embodiment, the bearing balls may be made of metal, and may be
arranged in a 6.times.9 matrix.
[0077] Referring back to FIG. 3, a spatial calibration algorithm
for projecting a particular location on the C-arm image onto the
affected part is described.
[0078] In each coordinate system for spatial calibration between
the C-arm 10 and the line projection module 50, as shown in FIG. 3,
{C} denotes the C-arm image coordinate system, {L} denotes the line
projection module coordinate system, {W} denotes the calibration
tool coordinate system, and when finding .sup.L.sub.CT in the
positional relationship of each coordinates, it is possible to
convert the coordinates on the C-arm image into points of the line
projection module coordinate system.
[0079] When expressing this as equation, the following Equation 1
and Equation 2 are given.
.sup.L.sub.CT=.sup.L.sub.WT.sup.W.sub.CT Equation 1
.sup.LP=.sup.L.sub.CT.sup.CP Equation 2
[0080] In this instance, is a conversion matrix for converting {b}
coordinate system into {a} coordinate system.
[0081] When finding .sup.C.sub.LT, one point of {C} coordinate
system may be expressed as one point of {L} coordinate system.
[0082] Here, when it is assumed that the intrinsic parameter of the
C-arm 10 is known, .sup.W.sub.CT can be calculated by finding the
extrinsic parameter of the calibration tool 70.
[0083] .sup.L.sub.WT may be calculated by projecting a preset
pattern from the line projection module 50 using a laser and
placing the calibration tool 70 at the location. In detail, the
laser pattern with the set origin, distance and shape is emitted,
and {W} is manually aligned with the pattern.
[0084] That is to say, using the set intrinsic parameter of the
C-arm and the extrinsic parameter of the calibration tool 70, a
conversion matrix between the C-arm image coordinates and the line
projection module coordinates is derived. Through this, by matching
the coordinates of the origin of the C-arm image coordinates and
the line projection module coordinates, the projection image having
undergone calibration of the coordinates of the C-arm image and the
line projection module coordinates may be accurately projected onto
the affected part.
[0085] The design of the calibration tool 70 is important to
increase the accuracy of and the calibration tool 70 may be
designed as shown in FIG. 4 and manufactured as shown in FIG. 5 (5A
to 5D) in consideration of linearity of light. However, this is
only provided as an example, and modification may be made to the
design of the pattern according to the user's needs.
[0086] Referring to FIG. 6, an image of the calibration tool 70
scanned by the C-arm 10 is shown. Additionally, in the laser
targeting projection experiment, a test apparatus and environment
for testing a quantitative target are created.
[0087] The screen is placed at 400 mm distance from the line
projection module 50, projection is performed by connecting
indicator points designated by a mouse with a laser line in the
range of width 150 mm (20 degrees) and height 120 mm (17 degrees),
and at this time, a distance error and an angle error are
calculated.
[0088] In this instance, a laser projected image is shown in FIG.
7. The point is the indicator point, and the line is the laser
projection line connecting the indicator points. The point where
the projection line turns is a laser projection location
corresponding to the indicator point.
[0089] Additionally, average distance errors of row and column and
maximum/minimum error values are shown in FIG. 8.
[0090] Referring to FIG. 8, it is a diagram showing projection
precision vs targeting distance, FIG. 8A shows distance error vs
projection column, and FIG. 8B shows distance error vs projection
row. A bar indicates an average of distance errors in row/column,
and an error bar indicates minimum/maximum values.
[0091] An overall average of distance errors is 1.5 mm, a standard
deviation is 1.9, and a maximum error value is 7.5 mm. The actually
measured angle error is 2.degree. or less. Accordingly, it can be
seen that it is possible to achieve precise calibration of the
laser targeting projector and the C-arm image according to the
present disclosure.
[0092] According to the present disclosure, it is possible to
indicate a variety of surgery information including osteotomy
lines, needle trajectories and pin insertion position and insertion
angle, thereby achieving accurate surgery as planned, and reducing
the likelihood of surgical errors and medical malpractice. Further,
it is possible to achieve quick and accurate surgery according to
the imaging plan while reducing the dose of radiation exposure to
the surgeon.
[0093] FIG. 9 is a flowchart of a method for calibration of a laser
targeting projector and a C-arm image according to an embodiment of
the present disclosure.
[0094] The method for calibration of a laser targeting projector
and a C-arm image according to this embodiment is performed by a
laser surgical guidance system including a C-arm fluoroscopy
(hereinafter, C-arm) to identify a patient's condition and support
a surgical plan, and a laser targeting projector to project a line
of the surgical plan directly onto an affected part through a line
projection module that generates a laser.
[0095] The method for calibration of a laser targeting projector
and a C-arm image according to this embodiment may be performed in
substantially the same configuration as the system 1 of FIG. 1.
Accordingly, the same element as the system 1 of FIG. 1 is given
the same reference sign, and redundant descriptions are omitted
herein.
[0096] Additionally, the method for calibration of a laser
targeting projector and a C-arm image according to this embodiment
may be performed by software (application) for performing
calibration of the laser targeting projector and the C-arm
image.
[0097] Referring to FIG. 9, the method for calibration of a laser
targeting projector and a C-arm image according to this embodiment
includes generating a particular laser pattern from the line
projection module 50 S10.
[0098] The particular laser pattern generated from the line
projection module 50 passes through the calibration tool 70 spaced
apart a predetermined distance from the line projection module 50
and including the collimator having the particular orientation
S30.
[0099] The pattern of the collimator may be configured under the
assumption that the laser beam comes from one point (a pin hole)
after being reflected at the Galvanometer. That is, the collimator
may be formed in an enlarged pattern having the same shape as the
particular laser pattern outputted from the line projection
module.
[0100] The collimator of the light pattern matching unit 71 is
formed in an opening pattern, and the opening pattern is formed at
a predetermined angle. That is, as shown in FIG. 4, light passes
through the collimator obliquely according to the properties of
light such as linearity, orientation and scattering.
[0101] The laser pattern having passed through the collimator of
the calibration tool 70 is displayed on the C-arm marker unit 75
having the bearing balls arranged in a matrix via the screen. The
bearing balls may be made of metal so that it can be recognized by
the C-arm 10, and may be arranged in a 6.times.9 matrix.
[0102] The laser pattern having passed through the collimator can
be recognized by the C-arm 10, and using this, the extrinsic
parameter of the calibration tool 70 is calculated by the C-arm
marker unit 75 (S50).
[0103] The coordinates of the C-arm image are converted into line
projection module coordinates using the extrinsic parameter
calculated in S50 (S90). To this end, first, a conversion matrix
between the C-arm image coordinates and the line projection module
coordinates may be derived using the preset intrinsic parameter of
the C-arm and the extrinsic parameter of the calibration tool
(S70).
[0104] Specifically, the spatial calibration algorithm for
projecting a particular location on the C-arm image onto the
affected part is described above. Accordingly, it is possible to
provide precise laser guidance by projecting a projection image
having undergone calibration of the coordinates of the C-arm image
and the line projection module coordinates directly onto the
affected part.
[0105] The method for calibration of a laser targeting projector
and a C-arm image may be implemented as an application or in the
form of program commands that may be executed through various
computer components and may be recorded in computer-readable
recording media. The computer-readable recording media may include
program commands, data files and data structures, alone or in
combination.
[0106] The program commands recorded in the computer-readable
recording media may be specially designed and configured for the
present disclosure, and may be those known and available to those
having ordinary skill in the field of computer software.
[0107] Examples of the computer-readable recording media include
hardware devices specially designed to store and execute program
commands, for example, magnetic media such as hard disk, floppy
disk and magnetic tape, optical media such as CD-ROM and DVD,
magneto-optical media such as floptical disk, and ROM, RAM and
flash memory.
[0108] Examples of the program command include machine code
generated by a compiler as well as high-level language code that
can be executed by a computer using an interpreter. The hardware
device may be configured to act as one or more software modules to
perform the processing according to the present disclosure, or vice
versa.
[0109] While the present disclosure has been hereinabove described
with reference to the embodiments, it will be appreciated by those
having ordinary skill in the technical field pertaining to the
present disclosure that various modifications and changes may be
made thereto without departing from the spirit and scope of the
present disclosure defined in the appended claims.
INDUSTRIAL APPLICABILITY
[0110] The present disclosure can be used in various fields of
surgeries using C-arms and is easy to enter the market due to the
low medical equipment grade. Additionally, it is possible to
directly manufacture/sale in the form of a module in existing
C-arms, and enter the market by technology transfer to C-arm
manufacturing companies.
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